Ethical hacking tutorials

Inside Windows Product Activation

A Fully Licensed Paper

July 2001

Fully Licensed GmbH, Rudower Chaussee 29, 12489 Berlin, Germany

ht*p://www.licenturion.com


>> INTRODUCTION

The current public discussion of Windows Product Activation (WPA) is
characterized by uncertainty and speculation. In this paper we supply
the technical details of WPA - as implemented in Windows XP - that
Microsoft should have published long ago.

While we strongly believe that every software vendor has the right to
enforce the licensing terms governing the use of a piece of licensed
software by technical means, we also do believe that each individual
has the right to detailed knowledge about the full implications of the
employed means and possible limitations imposed by it on software
usage.

In this paper we answer what we think are currently the two most
important open questions related to Windows Product Activation.

* Exactly what information is transmitted during activation?

* How do hardware modifications affect an already activated
installation of Windows XP?

Our answers to these questions are based on Windows XP Release
Candidate 1 (build 2505). Later builds as well as the final version of
Windows XP might differ from build 2505, e.g. in the employed
cryptographic keys or the layout of some of the data
structures.

However, beyond such minor modifications we expect Microsoft to cling
to the general architecture of their activation mechanism. Thus, we
are convinced that the answers provided by this paper will still be
useful when the final version of Windows XP ships.

This paper supplies in-depth technical information about the inner
workings of WPA. Still, the discussion is a little vague at some
points in order not to facilitate the task of an attacker attempting
to circumvent the license enforcement supplied by the activation
mechanism.

XPDec, a command line utility suitable for verifying the presented
information, can be obtained from http://www.licenturion.com/xp/. It
implements the algorithms presented in this paper. Reading its source
code, which is available from the same location, is highly
recommended.

We have removed an important cryptographic key from the XPDec source
code. Recompiling the source code will thus fail to produce a working
executable. The XPDec executable on our website, however, contains
this key and is fully functional.

So, download the source code to learn about the inner workings of WPA,
but obtain the executable to experiment with your installation of
Windows XP.

We expect the reader to be familiar with the general procedure of
Windows Product Activation.